Transistor magnetic-core multivibrator with constant current output



W. A. GEYGER TRANSISTOR MAGNETIC-CORE MULTIVIBRATOR WITH CONSTANT CURRENT OUTPUT Filed July 13, 1961 April 6, 1965 INVEN TOR. WILLIAM A. GEYGER transistors Q and Q".

United States Patent 3,177,447 TRANSISTOR MAGNETIC-CORE MULTIVIBRATGR WITH CONSTANT CURRENT OUTPUT William A. Geyger, Takoma Park, Md., assignor to the United States of America as represented by the Secretary of the Navy Filed July 13, 1961, Ser. No. 123,908 1 Claim. (Cl. 331-109) (Granted under Title 35, US. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to a constant current device and more particularly to a magnetic amplifier supplied by an A.C. voltage from a transistor magnetic core multivib-rator and having an inductor in the input circuit of the magnetic amplifier.

It is known in a transistor core magnetic vibrator circuit that the frequency of the output voltage varies with the potential of the D.C. input voltage source used for energizing the circuit. It may normally be expected that when batteries are used for the D.C. voltage source, the potential of these batteries may decrease, for example, as a result of weakening from age or use. With this invention an inductance is employed in the bias circuit of a magnetic amplifier in order to compensate for the effects of variations in the potential of the D.C. voltage source of the multivibrator.

An object of this invention is to provide a magnetic amplifier operated from a transistor multivibrator with a means for compensating for voltage and frequency variations in the output of the multivibrator.

Another object of this invention is to provide an inductor in the bias circuit of a magnetic amplifier.

A further object of this invention is to provide an inductor in the bias circuit of a magnetic amplifier fed from a transistor magnetic core multivibrator.

A still further object is to provide a new and improved means to compensate for variations in the supply voltage to a magnetic amplifier circuit.

Another object of this invention is to provide for a constant current flow in the load circuit of a magnetic am- Other objects and many of the advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing in which like reference numerals designate like parts throughout the drawing and wherein:

The drawing illustrates an embodiment of a magnetic amplifier with a constant current load circuit.

Referring now to the drawing, a transistor magnetic core multivibrator is illustrated having transformer 11 and Core 13 of transformer 11 has windings 15, 17, 19, and 21. Windings 15 and 21 are center tapped. One half of winding 15 is connected to the collector terminal of transistor Q and to the negative terminal of a D.C. Voltage source B The other half of winding 15 is connected to the collector terminal of transistor Q" and to the positive terminal of D.C. source 23. Winding 17 is connected to emitter terminal of transistor Q and to the positive terminal of D.C. voltage source 23 and Winding 19 is connected to the emitter terminal of transistor Q and to the positive terminal of the D.C. voltage source E The center-tapped secondary on output winding 21 is connected to the gate circuit of a magnetic amplifier. More specifically, the secondary or output winding 21 is connected through diodes 25 and 27 to the load or gate windings 12A and 14A of cores 12 and 14 of a magnetic amplifier circuit. Bias windings 12B and 14B of the magnetic amplifier are connected to' the D.C. terminals of full-wave rectifier 29. Rectifier 29 is connected through inductor L to the secondary or output winding of transformer 11 of the multivibrator. Feedback windings 12F and 14? on cores 12 and 14 respectively are connected to resistor 31. Feed-back windings 12F and 14F are connected by conductor 33 to the gate circuit of the magnetic amplifier and by resistor tap 35 through load 37 to the center tap of winding 21 of the multivibrator whereby one variable D.C. voltage may be supplied to the feed-back windings. Control windings 12C and 140 are provided on cores 12 and 14 respectively and a control circuit for the magnetic amplifier includes Windings 12C, 140, a source of D.C. control or signal voltage E and a resistor 39.

In operation, an alternating voltage E is supplied at the terminals of winding 21 of the multivibrator. Alternating voltage E is fed to the load circuit and the feedback circuits of the magnetic amplifier through diodes 25 and 27 and through load 37 to resistor 31 and through conductor 33. The amount of current flowing in the load circuit, including load 37, may be determined initially by adjusting the setting of tap 35 of resistor 33. After the load current value is thus established, the variations in load current will be controlled by and directly proportional to the D.C. signal applied to the control circuit.

Should the voltage of source E drop, due, for example, to the aging or weakening of batteries of source E the frequency and potential of the A.C. output voltage E will be correspondingly reduced. The reduction of the potential and frequency of E applied to the load circuit of the magnetic amplifier will tend to cause a reduction in the current flow through load 37. However, the voltage E having a reduced potential and frequency is also applied to the bias circuit through inductor L and rectifier to the windings 12B and 14B of the bias circuit. Since the frequency as well as the potential of E has been reduce-d, the inductive reactance of inductor is decreased and an increase in current flow through the windings 12B and 14B results, effecting the magnetization level of cores 12 and 14 in such a manner that the effective resistance of Windings 12A and 14A are reduced and the current fiow through the load circuit is maintained at the same value as it was previous to the reduction of the potential and frequency of E Similarly, if for the same reason the potential and frequency of E should increase, the inductive re-actance of inductor L would increase, reducing the current flow through windings 12B and 14B with a resultant increase in the effective resistance of windings 12A and 14A. The current flow through load 37 will again remain constant. In this manner a constant current is maintained through the load circuit when variations in the supply voltage E occur.

Obviously many modifications and variations of the present invention are made possible in the light of the above teachings. It is therefore to be understood, that within the scope of the appended claim, the invention may be practiced otherwise than as specifically described.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

A magnetic amplifier having a first saturable reactor means and a second saturable reactor means, said first saturable reactor means comprising a first saturable core, a first gate winding on said first core, a first bias winding on said first core, a first control winding on said first core, and a first feedback winding on said first core, said sec- 0nd saturable reactor comprising a second saturable core,

output circuit of said multivibrator including an output winding having a center tap thereon, first rectifier means connecting a first end of said output winding to a first end of said first gate winding, a first juncture, a second end of said first gate winding and a first end of said second gate winding being connected to said first juncture, rectifier means connecting a second end of said output winding to a second end of said second gate Winding, inductor means, said inductor means having a figure of merit which is sufficient to perform an integrating function, full wave rectifier means, said full wave rectifier means having an input circuit and an output circuit, means serially connecting the input circuitof said full wave rectifier means and said inductor means to the first and second ends of said output winding, means serially connecting said first and second bias windings to the output circuit of said full wave rectifier means, a control signal source, means serially connecting said first control winding and said second control winding to said control signal source, variable'resistance means having a movable tap, means serially connecting said first feedback winding and said second feedback Winding to said variable resistance means to form a feedback circuit, conductor means connecting said first juncture to said feedback circuit, load means, saidload means being connected between said variable tap on said resistance means and said center tap on said output winding.

References Cited by the Examiner UNITED STATES PATENTS 2,700,130 1/55 Geyger. 7 2,852,730 9/58 Magnuski. 3,111,621 11/63 Spinks 323-89X V FOREIGN PATENTS 558,410 6/58 Canada. 567,923 3/45 Great Britain.

ROY LAKE, Primary Examiner. ARTHUR GAUSS, Examiner. 

